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Donald K. Burleson

Oracle Utilities Tips

Low Level Tracing With oradebug

The oradebug utility falls into the “hidden” classification of utilities due to the lack of available documentation. The utility is invoked directly from SQL*Plus beginning in version 8.1.5 and Server Manager in releases prior to that. The utility can trace a user session as well as perform many other, more global database tracing functions.

oradebug requires the SYSDBA privilege to execute (connect internal on older Oracle versions). The list of oradebug options can be viewed by typing oradebug help at the SQL*Plus prompt:

SQL> oradebug help
HELP [command] Describe one or all commands
SETMYPID Debug current process
SETOSPID <ospid> Set OS pid of process to debug
SETORAPID <orapid> ['force'] Set Oracle pid of process to debug
DUMP <dump_name> <lvl> [addr] Invoke named dump
DUMPSGA [bytes] Dump fixed SGA
DUMPLIST Print a list of available dumps
EVENT <text> Set trace event in process
SESSION_EVENT <text> Set trace event in session
DUMPVAR <p|s|uga> <name> [level] Print/dump a fixed PGA/SGA/UGA variable
SETVAR <p|s|uga> <name> <value> Modify a fixed PGA/SGA/UGA variable
PEEK <addr> <len> [level] Print/Dump memory
POKE <addr> <len> <value> Modify memory
WAKEUP <orapid> Wake up Oracle process
SUSPEND Suspend execution
RESUME Resume execution
FLUSH Flush pending writes to trace file
CLOSE_TRACE Close trace file
TRACEFILE_NAME Get name of trace file
LKDEBUG Invoke global enqueue service debugger
NSDBX Invoke CGS name-service debugger
-G <Inst-List | def | all> Parallel oradebug command prefix
-R <Inst-List | def | all> Parallel oradebug prefix (return output
SETINST <instance# .. | all> Set instance list in double quotes
SGATOFILE <SGA dump dir> Dump SGA to file; dirname in double quotes
DMPCOWSGA <SGA dump dir> Dump & map SGA as COW; dirname in double quotes
MAPCOWSGA <SGA dump dir> Map SGA as COW; dirname in double quotes
HANGanalyze [level] Analyze system hang
FFBEGIN Flash Freeze the Instance
FFDEREGISTER FF deregister instance from cluster
FFTERMINST Call exit and terminate instance
FFRESUMEINST Resume the flash frozen instance
FFSTATUS Flash freeze status of instance
SKDSTTPCS <ifname> <ofname> Helps translate PCs to names
WATCH <address> <len> <self|exist|all|target> Watch a region of memory
DELETE <local|global|target> watchpoint <id> Delete a watchpoint
SHOW <local|global|target> watchpoints Show watchpoints
CORE Dump core without crashing process
UNLIMIT Unlimit the size of the trace file
PROCSTAT Dump process statistics
CALL <func> [arg1] ... [argn] Invoke function with arguments

Identical to tkprof, oradebug depends on trace files to store its output. These files are in the same location as specified by the user_dump_dest initialization parameter. The trace files are named according to the SPID of the process where the oradebug command is executed – the same naming scheme as described earlier.

Some of the oradebug options apply to a particular session and therefore require a system process id (SPID) as obtained from v$process. Other options are more global in nature and can be executed without attaching to any session.

For more details on Oracle utilities, see the book "Advanced Oracle Utilities" by Bert Scalzo, Donald K. Burleson, and Steve Callan.

You can buy it direct from the publisher for 30% off directly from Rampant TechPress.


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